Control system



R. H. ELLIS 1,851,760

CONTROL SYS TEM March 29, 1932.

Filed Aug. 14, 1950 2 Sheets-Sheet 1 INVENTOR I l WITNESSES March 29, 1932. R H Ems 1,851,760

CONTROL SYSTEM Filed Aug. 14, 1930 2 Sheets-Sheet 2 wlfuessss I I "i /2: :26;

P aiented 29, 1932 H. ZPETIEB'QBGH, rmswwmm N GER-TI flies-21 Augm's M, 21939;

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Another object is m pmvide for autmnati= (rally varyz'm @he speed of 0m mofior in ac cordance Evita iha tmque developed by 3% and I w s that @E a mam? p in @E A mare mwbiwim dojwb is in pmvifle for spec-2d @E the Lame-$3 0 flayed for it finm the will or reels. Fm @pamting the be $3 and iwsmlfly su pzpamsd by reels a pair of motors 7 and 8 suitably coupled to them by a pair of shafts ,9 and 11 respectively, are employed.

In the embodiment of the invention shown in the drawin and construction and of the reversible direct current type, are provided to accommodate the demands of the reels and for operating them a source of direct current power is provided by a pair of line conductors L and L.

For controlling the operation of whichever of the motors 7 and 8 is selected to drive its associated reel-as a winding reel, a current tension regulator 12 is employed. This regulator consists chiefly of an actuating coil 12a, which is connected in the armature circuit of the motor being controlled by it, a resistor 12?), which is connected in the field circuit,

and a resistor short circuiting vibrator 120, which is adapted to function in a well known manner in response to the current condition of the coil to vary the effect of the resistor in the field circuit and thereby vary the speed ofthe motor to which it is connected in accordance with the load or torque on the motor.

To provide for utilizing the one regulator for controlling both motors, its actuating coil is connected in a circuit extending from conductor L through a pair of contact members 13a and 13b of a multiple pole multiple throw switch 13, an automatic starting device 14, and an interlock 15b of a starting relay 15, toline conductor L The switch 13, as will appear more clearly hereinafter,

is employed for reversing the operations of the two motors, and the relay 15 for establishing the various actuating circuits when the mill is set in operation.

Associated with contact members Band 135 on one side of switch 13 are a pair of I cooperating contact elements 130/ and 13b to which the armature 7a-of motor 7 is connected. On the opposite side. of the switch to these elements another pair of-contact elements 13a" and 136" are arranged and to them the armature 8a of the motor 8 is connected. Through the agency of these contact membersand elements, when switch 13 is thrown in one direction the armature of one motor is connected to the source of supply through coil 12a of the regulator, and when thrown in the other direction the armature of the other motor is so connected. By reason of such arrangement coil 12a is rendered responsive to the armature current of whichever of the motors is connected to the source of-current supply and when connected in such motors 7 and 8 of similar size resistor 12b, and a pair of contact members 130 and 13d of switch 13, to line conductor L Associated with the contact elements 130 and 13d and on opposite sides'of the switch are two sets of cooperating contact elements 130 and 13d and 130 and 1311" to which the field windings 7b and 86 respectively of the motors 7 and 8 are connected. The arrangement of these connections are such that when .the switch 13 is thrown to connect coil 12a in the armature circuit of one of the motors it also connects the resistor 12b in the field circuit of the same motor.

As shown in Fig. 2 of the drawings, when switch 13 is thrown to its upper position, the current regulator is connected in the field and armature circuits of motor 7, and when thrown to its lower armature circuits 0 motor 8. Hence, when switch 13 is thrown to connect either one of the motors to operate as a windin reel motor, the regulator coil 12a is excited in accordance with the current passing through its armature, which is proportional to the torque developed thereby, or, in other words, the tension in the strip being wound on the reel actuated by it. Consequently, as the tension osition, in the field and to actuate the reel employed as an unwinding I reel when the other motor is connected to conductors L and L to operate its associated reel as a winding reel, a motor generator set consisting of a motor 16 and a generator 17 is employed. The motor of this set is so designed that its speed varies inversely as the strength of its field, and the generator is so designed that it produces a voltage which varies directly as its speed, which is the same as that of the motor.

To operate the motor 16 its armature 160, is connected in a circuit extending from line conductor L through an interlock of relay 15, the armature itself to line conductor L and its field windings 1612 are adapted by means of a relay 10 to be excited when the mill is first started by current received from line conductors L, and L and after the mill has been brought up to a predetermined speed to one or the other of a pair of pilot generators 18 and 19 coupled by means of shafts 18c and respectivelyto the motors 7- and 8, the one to which the windings are connected beingthe one coupled to the motor which is excited to operate its associated reel as a winding reel.

. For starting a circuit is provided for windings 166, the circuit extending from line conductor L through a variable resistor 21 by its upon motor is it will tend to run away.

nasryco means of which the excitation of the motor may be manually controlled, through inter= lock 15d of relay 15, back contact member 10?) of relay 10, windings 16b, and back contact member 100 of relay 10 to line conductor L The actuating coil 10a of relay 10 is connected by means of conductors 10m and 10; to the contact members 13a and 13b of switch 13, whereby such coil is rendered responsive to the counterelectromotive force of whichever of the motors 7 and 8 is connected to the line conductors L and L and the coil is so designed that it will not lift the back contact members 10?) and 100 from their seat until the counterelectromotive force in the motor to which the coil is responsive is built up to a value corresponding to a preselected operating speed of the motor. The reason for providing for impressing the line voltage upon the windings 16?) when the mill is first started, is that at such time there is no voltage produced by the pilot generators 18 or 19, and it no field or insufiicient field is impressed such were permitted, generator 17 would also run at an excessively high rate of speed and cause the unwinding reel motor connected to it, as will presently appear, to also run at an excessive speed, the result of which would probably be that the strip would get tangled up between the unwinding reel and the mill, or at least no tension would be produced in the strip between such points.

After the mill is brought up to speed and coil 10a of relay 10 is sufiiciently excited to lift its contact members, the circuitextending from line conductors L and L through the windings 16b is opened and the winding connected through interlocks 10d and 10a to a pair of contact members 13c and 13f of switch 13. Associated with these contact members on opposite sides of switch 13 are two sets of contact elements 136 and 13f and 13a" and 13f", to whicharmature 19a of pilot generator 19 and armature 18a of generator 18 are connected; variable resistors 22 and 23, respectively, being connected in series with these armatures for manually varying their output to assist in adjusting the system for operation. As will be appreciated from the foregoing, when the switch 13 is thrown to its upper position as viewed in Fig. 2 of the drawings, the armature of the pilot generator 18 is connected to the field windings 16b of motor 16,- and when thrown to its lower position the armature of generator 19 is connected to such windings. Since these generators are driven by motors 7 and 8 and the motor 16 is so designed that it varies in speed inversely to the strength of its field, the motor generator set is caused to vary in speed inversely'to the speed of whichever motor is connected to operate as a winding reel motor. Furthermore, as its speed determines its output the voltage produced by generator 17 varlies inversely to the speed of the winding ree For operating motors 'Z and 8 as unwindin reel motors, armature 17a of generator 17 is connected through a startingdevice 24 to a pair of contact members 139 and 131% of switch 13. Associated with these contact members, and on opposite sides of the switch 13, are two sets of contact elements 13g and 13k and 13g" and 13% To the contact elements 13g and 137?. the armature 8c of the motor 8 is connected, and to the contact elements 13g and 1371," the armature of the motor 7 is connected. By reason of these connections, when the switch 13 is thrown to its upper position and the motor 7a thereby connected to the source of supply or to line conductors L, and L the armature 8a of the motor 8 is connected to the armature 17a of the generator 17 whereb motor 8 is caused to rotate at a speed varying in proportion to that of the current produced by generator 17, which, as has been explained hereinbeiore, is varied inversely as the speed of motor 7. Consequently, the unwinding reel 6 will be caused to vary in an inverse ratio to that of the winding reel 5, and hence the ripheral speed of the two thereby maintained lhe same, which is desired.

To provide a field for motors 7 and 8 when they are connected to operate their associated reels as unwinding reels, their field windings are connected to oppositely disposed sets of contact elements 135 and 137'" and 132" and 13 respectively, on switch 13. lnterposed in cooperative relation between these sets of contact elements are a pair of contact members 132' and 137', which are in turn connected with the line conductors L and L In series with these contact members there is provided a variable resistor 25 for manually varying the speed of the unwinding reel motor, so that it can he set to normally operate the reel at a sufiiciently lower peripheral speed than the linear speed of the strip to produce the desired back tension.

To provide excitation for thepilot generators 18 and 19, field windings 186 are connected in a circuit extending from line conductor L through a variable resistor 26. the field windings 18b and an interlock 15c of relay 15, to line conductor L and field windlugs-19b in a circuit extending from line conductor L through a variable resistor 27, the field windings 19b and an interlock 15; of relay 15 to line conductor L The variable resistors are provided to assist in adjusting the system for operation.

For exciting the field windings 17b of generator 17 a circuit is provided which extends from line conductor L through variable resistor 28, the field windings 17b, and interlock 159 to line conductor L As stated hereinbefore, relay 15 is emtrolled thereby, and when opened, coil 15a is deenergized, permitting the interlocks to fall open.

Before starting the mill in operation, line conductors L, and L are energized through the closure of a line switch 31. The switch 13 is then operated to either its upper or lower position, depending upon the direction in which it IS desired to pass the strip through the mill. With the closure of the switch 13 the reel motors are ready for operation. Thereafter, switch 29 is closed, closing relay 15 and setting the system in operation.

With the closure of relay 15, assuming that switch 13 is thrown to its upper position, mo-

tor 7 will be connected to the line conductors L, and L through the circuits hereinbefore traced, and motor 8 to the armature of the generator 17. At the instance of starting through the operation of the starting devices 14 and 24 the motors will be gradually brought up to speed. As motor 7 approaches normal operating speed, relay 10 operates,

shifting the excitation of the field windings 16b of the motor 16 from line conductors L, and L to the armature 180 of pilot generator 18. Thereafter the motor generator is caused .to function at a speed which varies inversely to that of motor 7 which is controlled byregulator 12. Due tothis the output of the generator is varied inversely as the speed of motor 7 and consequently the speed of motor 8 is also varied inversely as that of motor 7. From this it follows that the speed of the unwinding reel is varied inversely to the speed of the winding reel 5. Hence as the diameter of the winding reel increases tending to increase the linear speed of the strip and thereby the tension in it, the speed of the winding reel motor is decreased, and that of the unwinding reel increased, maintaining the peripheral speeds of the two reels substantially constant as well as thetension in the strip.

After the strip has been passed through position and the mill is then ready for operation in the reverse direction. Thereafter with the reclosing of switch 29 the strip will be passed back through the mill in the same manner and under the same operating conditions that it was originally passed through the mill. Such operations may be repeated as many times as is desired in the working of stri A will be readily appreciated by those skilled in the art, although switch 13 is illustrated and described here as a manually operable reversing switch, it may be replaced by an automatic switch which may be rendered responsive to the travel of the strip and the reversing of the mill thereby efiected automatically.

According to the provisions of the patent statutes, I have explained the principle and operation of my invention, and have illustrated and described what I now consider to be its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In a control system, an electric work motor, means for automatically varying the speed of said motor in accordance with the torque developed by it, a second motor, and means responsive to the speed of the first motor for varying the speed of the second motor in inverse proportions to that of the first.

, 2. In a control system, a pair of electric motors, means for automatically varying the speed of one of said motors in accordance with the torque developed by it, means responsive to the speed of said motor for verying the speed of the other in inverse proportion to that of the first, and means for reversing the operation of the two.

- 3. The combination with a pair of reels having a pair of electric motors cou led thereto for passing strip through a rolling mill, a sourceof current supply, means for connecting one of said motors to operate its associated reel as a winding reel, means for connecting the other motor to operate its associated reel as an unwinding reel, means for automatically reducing the speed of the winding reel motor in accordance with the tension of the strip, and means responsive to the speed of the winding reel motor for increasing the speed of the unwinding reel motor in the same, proportion that the speed of the winding reel motor is decreased.

4. The combination with a pair of reels having a pair of electric motors coupled thereto for passing strip through a rolling mill, of a source of current supply, means for connecting one of said motor. to operate its associated reel as a. winding reel, means for connecting the other motor to operate its associated reel as an unwinding reel, means for automatically reducing the speed of the winding reel motor in accordance witht-he tension of the stri means responsive to the speed of the windlng reel'motor for increasing the speed of the unwinding reel motor and in the same proportion that the speed are of the winding reel motor is decreased, and means for reversing the operation of the two motors and their control with respect to each other.

5. The combination with a pair of reels having a pair of electric motors cou led thereto for passing strip through a ro lingmill, of a current type regulator connected in the operating circuits of one of said motors to control the speed thereof in accordance with the torque developed by it whereby to render the reel associated with said motor operative as a winding reel, and means responsive to the s eed oi? said winding reel motor for inversey varying the speed of the motor coupled to t; e other reel to render it operative as an unwinding reel.

6. A motor control system comprising a motor having means associated therewith for automatically varying its speed in accordance with the torque developed by it, a sec- 0nd motor designed to vary in speed inversely as the strength of its field, and means responsive to the speed of the first motor for varying the field of the second.

7 A. motor control system comprising a motor having means associated therewith for varying its speed in accordance with the torque developed by it, a second motor designed to vary in speed inversely as" the strength of its field, and a pilot coupled to said first motor for supp field for the second motor.

8. The combination with a pair of reels having electric motors thereto for passing strip through a rolling mill, of a source of current supply, means for connecting one of said motors to said current supply, means for varying the speed of said motor in accordance with the torque developed by it, a motor generator set designed to generate a voltage varying directly as the enerator ying the speed of its motor, means connecting the mothe other of said reel motors to the thereto for passing strip tor of said motor generator set to said source of current supply, means responsive to the speed of the torque controlled reel motor for controlling the speed of the motor of the motor generator set, and means connecting generator of said motor generator set. i

9. The combination with a pair of reels having electric motors operatively coupled through a rolling mill, of a source of current supply, means for connecting one of said motors to said current supply, means for varying the speed of said motor in accordance with the torque developed by it, a motor generator set designed to generate a voltage varying directly as the speed of its motor, means connecting the motor of said motor generator set to said source of current supply, means responsive to the speed of the torque controlled reel motor for controlling the speed of the motor of the motor generator set, means connecting the operatively coupledother of said reel motors to the generator of said motor generator set, and means for reversing the connections of said reel motors so that either may be connected to the source of current supply and either to the generator of the motor generator set and the speed of each thereby controlled by the speed or" the other.

10. A control system, comprising a pair of work motors, a current tension regulator adapted to vary the speed of the motor to which it is connected. in manner to maintain the torque on the motor constant, a motor generator set, means for connecting one of said Work motors to said source of current in circuit relation with said regulator, a pilot generator coupled to said torque controlled motor, means for connecting said pilot gen erator to supply the field tor the motor of said motor generator set, and means for connecting the other work motor to the generator of said motor generator set.

11. A control system, comprising a pair of work motors, a current tension regulator adapted to vary the speed of the motor to which it is connected in a manner to maintain the torque on the motor constant, a pilot generator coupled to each of said motors and adapted to generate a voltage varying directly as the speed of each motor, a motor generator set, a field winding for the motor of said set, and reversible means for connecting one of said motors to said source of current in circuit relation with said tension regulator, and for connecting the pilot generator coupled to said last-mentioned work motor to the field Winding of the motor of said motor generator set and for connecting the other of said work motors to the generator of the motor generator set.

12. A control system, comprising a pair of work motors, means for manually varying the speeds of said motors, a current tension regulator adapted to vary the speed of the motor to which it is connected in a manner to maintain the torque on the motor constant, a pilot generator adapted to generate a voltage varymg directly to its speed operably coupled to each of said work motors, means for manually varying the output of each of said generators, a motor generator set adapted to generate a voltage varying in direct proportion to its speed, a field winding for the motor of said set, and means for selectively connecting either of said work motors to said source of current supply through said regulator, the opposite work motor to the generator of said motor generator set and the field windings of the motor of the motor generator set to the pilot generator coupled to the motor in circuit relation with which the regulator is connected.

13. A control system comprising a pair of work motors, a current tension regulator adapted to vary the speed of the motor to lid which it is connected in a manner to maintain the torque on such motor constant, a source of current supply, means for connecting one of said motors to said current supply in circuit relation with said re ulator, a pilot generator operatively couple to the motor controlled by the regulator, e, field winding on said other work motor, means responsive to said regulator controlled motor for connecting sai source of current supply when the motors are first started and then autometicall disconnectin it from said source of supp y and to said pilot generator when the regulator controlled motor hes reached a predetermined speed.

In testimony whereof sign my name.

, soees'r rt. Ennis.

field winding to said 

